In machine tools such as boring mills or the like it is often necessary to change the work engaging tool implement, due either to wear of the tool or a required change in machining operation. To facilitate such changes, machine tools are provided with tool implement holders such as chucks or collets. Such holders provide a means for releasably connecting the tool implements with the machine tool in an enforced orientation in which the tool is aligned with the axis of rotation of the spindle through which the toolholder is driven.
There has recently been developed chuck devices which permit changing of the tool without necessitating stopping rotation of the chuck itself. This type of chuck saves both machine time and operator labor, and conserves energy required to start and stop the machine. One such chuck device is described in U.S. Pat. No. 3,599,996, issued to Donald G. Holt on Aug. 17, 1971.